1. Field of the Invention
The present invention relates to telecommunications and, more particularly, to a method of resource management for a mobile node, e.g., for a mobile node using Mobile IPv6.
2. Description of Related Art
Mobile IP has been used to allow mobile nodes to remain reachable when they move around in an Internet Protocol (IP) network. Mobile IP for IPv4 (MIPv4) is described in C. Perkins, “IP Mobility Support for IPv4,” Request for Comments 3344, August 2002, which is incorporated herein by reference. Mobile IP for IPv6 (MIPv6) is described in D. Johnson et al., “Mobility Support in IPv6,” Request for Comments 3775, June 2004, which is incorporated herein by reference.
In the Mobile IP approach, a mobile node is assigned a home address that routes to a home agent. When the mobile node is away from its home network (i.e., roaming), the mobile node registers a care-of address with the home agent, and the home agent maintains a mobility binding for the mobile node that associates the mobile node's home address with the mobile node's care-of address. Then, when the home agent receives packets addressed to the mobile node's home address, the home agent forwards the packets to the mobile node's care-of address. In this way, the mobile node can remain reachable at its home address even when its point of attachment to the IP network changes.
However, supporting Mobile IP consumes network resources. For example, a network element, such as a network access server (NAS) would typically allocate a care-of address to each roaming mobile node that the NAS is serving and a home agent would typically maintain a mobility binding for each roaming mobile node that the home agent is serving. When a mobile node stops using a given care-of address, the network resources associated with the care-of address may be freed up. For example, a NAS may de-allocate the mobile node's care-of address, so that it can be allocated to a different mobile node, and the home agent may be able to clear the mobile node's mobility binding (unless the mobile node obtains a new care-of address). Such resources are often associated with designated “lifetimes,” so that the resources can be cleared automatically when the lifetime expires. However, it is often beneficial to clear unneeded resources more quickly because “dangling” resources can create a significant impact on a network in terms of capacity and operational costs.
Accordingly, there is a need for methods of managing resources for a mobile node in a timely manner.